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Greenhouse Climate Control System

A Guide to Greenhouse Climate Control for Growers

By January 2, 2017July 1st, 2024No Comments
greenhouse climate control

There are three different ways to manage humidity levels in enclosed spaces. One is through manual operation of the system, typically with a separate hygrometer. The second option is using a timer. This allows fogging and misting systems to turn on and off at specific times. The third option is to install a humidity controller. This is a single-zone microprocessor that is designed with an internal humidity sensor as well as the capability to connect to an external sensor, if needed. Using this system in conjunction with your cooling system provides optimal results.

Whether you’re dealing with a large commercial greenhouse or a smaller greenhouse in the backyard, a fogging and misting system automatically monitored by a humidity controller is an ideal way to maintain optimal growing conditions. Easy to install and fully compatible with many different devices, humidification systems are cost-effective and provide a consistent environment in your greenhouse to allow your plants and crops to thrive.

The Challenges of Traditional Greenhouse Humidification Systems

Most greenhouse growers fight a continual battle against low humidity and high temperature, which can trigger plant water stress. If humidity drops below 30 percent, the growing process may slow to a halt. The problem can worsen each winter when cold weather reduces the moisture in the air. To assure consistent quality and production, greenhouse operators and growers are turning from traditional humidification techniques to a new method that dramatically improves humidification coverage, responsiveness and productivity while reducing water/energy use, maintenance and installation cost.

Plants lose most of their moisture from evaporation through their leaves, and get most of the carbon needed for growth from carbon dioxide through their leaves. Controlling plants’ pores by effectively controlling the climate can result in stronger, healthier plants with more growth potential. In this effort, fog systems are a proven way of providing needed humidification, as well as cooling via evaporation.

The challenge is that humidification coverage must be complete, uniform, and responsive to changing moisture levels in the air. It must keep all plants from getting too dry and too wet. Water vapor collecting in the wrong pattern, in fact, can “fall out” to create areas of wetness while other areas may remain too dry. In an age of tight budgets and rising commodity prices, thought also needs to be given to reducing water and energy use, and maintenance and installation cost. A number of traditional misting systems add moisture to the air in greenhouse applications. While these offer benefits, they’ve been limited by drawbacks. Typical humidification systems leave hot, cold, dry or wet zones, which have a lag time in mixing because the spray is directional.  This causes plant stress, less than optimal health and growth, and can hurt the bottom line.

Static Line Systems

Among high-pressure fog systems, which create and distribute tiny water droplets based on the humidity level needed in an area, static line systems and vertical fan systems have been common choices. With static line systems, which mount and align tubes and nozzles to deliver mist, uneven humidification distribution can be a problem. Moisture may not completely or uniformly evaporate into the surrounding air. Nozzles which spray a certain distance and direction can create areas of too much moisture or wetness under a nozzle. Other areas farther from mist-spraying nozzles may receive too little humidification.

With no airstream to spread humidification beyond the nozzle spray areas, it can be difficult to provide complete, uniform coverage and it can take longer to reach desired humidification levels. Water moisture “fall out” can increase water use and over-wet plants — making them more susceptible to disease, fungi and insects — while labor-intensive tubing alignment and mounting can increase installation and maintenance cost.

Vertical Fan Systems

A vertical fan humidification system adds an airstream to aid air moisture distribution, but a stationary airstream typically covers just a narrow band 25-degrees wide. Like a flashlight’s beam, this leaves many areas outside its focus. Humidification may be relatively slow to diffuse, with pockets of relative dryness remaining. Adding fan oscillation can distribute mist over a wider area, but still leave areas with less humidification while the airflow is pointed elsewhere. Turbulence is also created when airstreams cross, leading to increased “fallout” and water use with diminished humidification.

Air and water humidification systems, combining low-pressure water and high-pressure air to atomize water droplets, also have drawbacks for greenhouse use. These include high upfront costs for nozzles that combine air and water, expensive air compressors, and expensive separate lines for air and water. The cost of maintaining dual air-water systems typically runs high as well.

Factors Affecting Greenhouse Humidification

Most greenhouse applications require artificial humidification to maintain moisture levels that provide an ideal growing environment. High-pressure misting systems are a practical and effective option for controlling greenhouse humidity levels. Before considering the type of humidification system or system design, a good understanding of the environment is required. Consider these factors when choosing a greenhouse humidification system:

  • Size of the structure: If the greenhouse is empty, the volume of air to be humidified increases dramatically. Do not expect the same results from a system in a full greenhouse as compared to a system in an empty greenhouse.
  • Required Humidity Level: If there is too much air exchange, humidity levels will not increase beyond a certain point. That maximum achievable humidity level is directly related to the introduction of fresh air and the output capacity of the system.
  • Amount of Air Exchange: Restricting air exchange (or increasing mist system output) affects how quickly the required humidity level is achieved, and how often the system will cycle. Over a certain period of time (as long as fresh air is not constantly introduced), the mist system can provide humidity levels in excess of 90%. If the time it takes to accomplish the needed humidity level is too long for a specific application, the system flow should be increased.
  • Seasonal Ambient Temperature and Relative Humidity
  • Racking Structure Within the Greenhouse

Once the important factors have been accounted for, an appropriate mist system design can be created. In some cases, the design will include mist lines mounted overhead. In other cases, it will include a fan that incorporates an air stream into the mist to achieve a higher evaporation rate and better distribution of humidity.

Tips for Choosing the Correct Greenhouse Climate Control System

In the past, controlling humidity was a challenge because hygrometers did not have a control system that required constant monitoring and manual adjustments to increase or decrease humidity. Hygrometers also tended to be inaccurate — at least until technology advances led to amazingly accurate sensors and controllers. Today, automated microprocessor can both complete the measurement of moisture content in the air and automatically signal the system to adjust. This works exactly like the relay of electronic information and signals between a thermostat and a heater or air conditioner.

With modern, high-quality humidity controllers in place, your system can be set and maintained for humidity levels in a specific zone. These systems also have external sensors that can be wired into the system, allowing the controller and the sensor to be in different locations and still communicate. The system itself has two output relays and comes complete with a fully programmable delay start and stop. This allows the system to be set for your specific needs with the option to reconfigure the system as required as often as needed.

There are two different options for humidity sensors: low and high humidity sensors. In environments where the humidity will be maintained at a level of 10 to 70%, low humidity sensors will provide control for the vast majority of environments. Using standard sensors in high-humidity environments will damage the microchip. The high-humidity sensor is recommended where the humidity levels exceed 70%. These units are designed with specialized filters to protect the microchip, even in very high humidity environments. High-humidification systems can be used in greenhouses or other types of applications where humidity levels may reach as high as 97%. These sensors, even at this humidity, will be accurate to plus or minus 2%, which is considered one of the most accurate available today.

As with all of our products, Fogco humidity controller units are fully compatible with all of our fan systems. We also sell a full line of accessories for our sensors, controllers, and systems, including shielded cable, pin connectors, and conductor cables, providing everything you need to complete installation.

The Benefits of Fogco’s Automated Humidity Controllers

Overall, if greenhouse humidity isn’t properly controlled, even if off by a few percentage points, it can mean a loss of production, poor growth and quality, or even the complete loss of an entire growing season. Therefore, by using a humidity controller in your greenhouse space to help maintain proper humidity levels, you can ensure proper plant growth and development.

Our automated humidity controllers are designed with convenience and functionality in mind, ultimately resulting in systems that provide significant advantages over more manual processes. With a humidification system in place, there is no need to continually read the hygrometer or worry about the system turning on and off at pre-set times. Automated features ensure that the humidity level of the greenhouse remains constant, based on the actual climate conditions rather than a pre-set timer. Microprocessor controls operates with a high level of accuracy when measuring humidity levels, providing reliable readings. In conditions with up to 70% humidity, the microprocessor control can determine the humidity level with the precision of plus or minus two percent. For climates between 70% and 99% humidity, high humidity options are best, as they allow the same level of precision even at very high atmospheric moisture levels.

High Humidity Controllers

High humidity controllers have additional protection around the sensor chips, preventing excessive condensation buildup. Without this protection, very moist conditions will cause excess condensation and chip failure. With the additional protection, the chip will continue to provide highly accurate readings to automatically turn fogging and misting systems on and off.

Accurately measuring humidity levels is crucial to fully optimizing the benefits of humidity controllers. This is why microprocessor controls are so important. Leveraging these tools to monitor temperature and control climate and humidity levels, in combination with a cooling system, creates a fully automated system.

A Humidification Revolution

For greenhouse operators seeking to prevent growth or quality issues due to dry air-caused plant water stress, our Revolution and Evolution misting fans provide the ideal solution. We are a member of OFA, an association of floriculture professionals, so we understand what is required and we have systematically addressed the drawbacks of traditional greenhouse humidification and humidity control. Developed with customer input, our integrated climate control system can to achieve complete humidification of greenhouse areas up to 10,000 cubic feet without “fallout” or wetness.

If, like a flashlight, traditional static lines or vertical fans emit narrow “beams” of humidification, then the Revolution acts like a floodlight, bathing a whole area with humidification. What’s unique about the technology is how it achieves continuous, even, 360-degree humidification coverage. Hung like a simple ceiling fan, it broadcasts a fine “invisible mist” outward in a horizontal circle along a stream of air. By integrating the horizontal airstream with the fog, its micron-size water droplets stay suspended much farther and longer than traditional systems. This provides better, more even distribution of humidification, more complete evaporation, and virtually no “fallout.” Through flash evaporation temperatures can be reduced up to 30 F, and humidification levels can be maintained near 90 percent. By broadcasting a focused airstream mixed with fog in a full-circle, the Revolution can quickly eliminate the hot, cold, dry or wet zones that typical humidification systems leave behind.  By minimizing wetting from “fallout” there’s less susceptibility to disease, fungi and insects.

Because the Fogco unit can adapt to humidity or temperature changes up to three times faster than static line systems, plants continue growing longer and healthier within a tighter humidification and temperature range. Since the unit can adapt quickly to weather changes when used with a thermostat and humidistat, there’s more growing consistency. It gives growers the precision they need to create and maintain an ideal greenhouse growing environment without peaks and valleys of temperature and humidification.

A 360-degree vented mist system for humidification, the Revolution provides up to five times the coverage of static line systems with less water, maintenance and installation cost. With more even humidification coverage and less “fallout”, the unit can use a significantly smaller pump than traditional systems, which minimizes utility costs. Compared to static line systems, users of the unit can save up to 35% on water/electricity and up to 75% on water/electricity compared to vertical fan systems. In a time of budget constraints, the Revolution’s simplified installation can save resources too. Since it hangs like a ceiling fan, it reduces installation and maintenance cost. Its set up eliminates the need to work around poles, perimeters, columns, and changes in floor elevation, reducing labor cost and cutting installation time about 90% compared to static line system installation.

The Fogco Revolution can be mounted from any overhead structure, used indoor or out, and comes with an outdoor rated fan and powder coated enclosure. The mist system for humidification is portable when mounted from a custom stand. The system is designed to operate with any Fogco pulley-driven or direct-drive 1,000-psi fog pump, and is customizable by choice of appropriate Fogco nozzles.

Fogco Greenhouse Humidification Systems

Setting up a new commercial or residential greenhouse is a time for many important decisions. This is true no matter where you live, but in drier climates, having the correct humidity controller and misting system are essential for your greenhouse. At Fogco, we offer customizable designs to ensure humidification systems meet any and all requirements. Our cooling systems can control climate and temperature levels in small hobby greenhouses as well as large-scale commercial greenhouses. In fact, our systems can even be used in aquaculture operations to maintain constant humidity, assisting in temperature control and reduced evaporation in hot and dry climates.

We offer two different humidity controller units that are designed for specific humidity ranges and different requirements, based on the requirement of your greenhouse. From high-tech programmable options to those that are more streamlined and can be used in 1 zone for high precision control for even the most sensitive plants and crops. We also have the ability to integrate our mist systems with more robust environmental control systems that are already in place. Our team of experts is here to listen to your needs and recommend which controller will work best with your system.

Fogco has over a quarter of a century of experience working in the misting system and humidification industry. We have worked with small and large production greenhouses as well as a variety of industries to develop systems that are effective, efficient, and reliable, because we understand the importance of getting everything right.

If you are building a new greenhouse, contact us online or call us at 800-607-6478. We are happy to provide you with the solutions you need to effectively control the humidity in your greenhouse.

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